Palm power screw wrench



' July 7, 1970 s. R. PIERCE PALM POWER SCREW WRENCH Filed Oct. 9, 1967 2 Sheets-Sheet 2 FIG.3

III/III Ill/II lI/I FIG.4

II INVENTOR.

STANLEY R. PIERCE United States Patent M 3,519,046 PALM POWER SCREW WRENCH Stanley R. Pierce, Rte. 1, Box 148, Williamston, Mich. 48895 Filed Oct. 9, 1967, Ser. No. 673,639 Int. Cl. B25b 17/00 US. Cl. 145-66 3 Claims ABSTRACT OF THE DISCLOSURE A tool for installing threaded fasteners in places having a minimum amount of excess space and where speed or torque is desirable, the tool including a trigger operated mechanism contained within a pistol-grip case.

This invention relates generally to tools. More specifically it relates to tools for turning threaded fasteners.

A principal object of the present invention is to provide a palm-power screw wrench for the purpose of installing threaded fasteners in places with a minimum amount of access space and where speed or torque is desirable.

Another object of the present invention is to provide a palm-power screw wrench which would be superior to ordinary screwdrivers in similar situations by reason that the handle and energy source are off-set from the shaft delivering the force, and turning action.

Yet a further object of the present invention is to provide a palm-power screw wrench having a superior ability to hold in a steady position while the turning force is being delivered to a threaded fastener which is superior compared to the sometimes awkward grip of a handle of a conventional screw driver and the untrue swivel action of the human wrist which accordingly sometime results in misalignment of the screw driver shaft and thereby slipping off the screw head, or resulting in a crooked screw installation.

Other objects of the present invention are to provide a palm-power screw wrench which is simple in design, inexpensive to manufacture, rugged in construction, easy to use and efiicient in operation.

These and other objects will be readily evident upon a study of the following specification and the accompanying drawing wherein:

FIG. 1 is a side elevation view of the present invention shown in operative use;

FIG. 2 is an exploded side elevation view of the parts which comprise the present invention;

FIG. 3 is a side elevation view of the hollow case;

FIG. 4 is a cut-away view of a rear end elevation with right and left halves cut away; and

FIG. 5 is a cut-away view of a rear end elevation similar to FIG. 4.

Referring now to the drawing in detail, reference numeral represents a palm-power screw wrench, according to the present invention, wherein there is a pistol-grip case made of high impact plastic or light metal alloy and which is of the size to comfortably fit the average size hand, the pistol-grip case 11 comprising a left-hand 12 and a right hand half 13 which are provided with a plurality of openings 14 for purpose of receiving securement screws 15 therebetween. The pistol grip case 11 is accordingly hollow so as to enclose a common ring and pinion gear 16 and 17, the gears facing each other.

The present construction further includes a finger-grip 18 having an integral gear rack 19 at its upper end. The finger-grip has an opening 20 for receiving a pin 21 therethrough, the pin being mounted within openings 22 of the pistol-grip case halves 12 and 13, thus providing pivotal means for the finger-grip 18. A shaft 23 having locking tabs grooves 24 near each opposite end carries a 3,519,046 Patented July 7,, 1970 sufficiently wide, smaller diameter spur gear 25 thereupon, the teeth 26 of the gear 25 being engaged with the teeth 27 of the gear rack 19. It is to be noted that the engaging teeth may be at an angle to provide a smooth ratchet action, if so preferred.

A drive shaft 28 carries a pinion gear 29 at one end, the teeth 30 of the pinion gear 29 being engageable with the ring gears 16 and 17. It is to be noted that the pinion gear may comprise a beveled gear as is indicated in FIG. 2 of the drawing. Bearings 31 are mounted in the barrel opening 32 of the pistol-grip case for purpose of supporting the drive shaft 28. A tool bit chuck 33 having friction-grip characteristics is adapted to screw driver bits, Allen-head bolts, small diameter wood drills and the like.

Locking tabs 34 serve to hold the differential in a proper position.

FIG. 3 is a side elevation of the hollow case 11 with certain parts (listed below) removed to show the arrangement of essential components in the assembled position. The following parts, numerically designated in FIG. 2 have been removed: Left half of case 12, left side ring bevel gear 16, left side locking tab 34a.

Describing the viewed right hand half of case 13, with remaining components in assembled position, finger-grip 18 with its integral gear rack 19 is secured to lower end of handle portion of case by means of a movable pin 21, inserted through matching holes 22, in right half of case 13 and left half 12 (not shown) and through corresponding hole 20, in lower end of finger-grip 18, giving it pivotal action allowing teeth 27, of gear rack 19 to enmesh in sequence from rear end to forward end with the teeth 26 of the spur gear 25 located on gear shaft 23 between ring bevel gear 17 and ring bevel gear 16 (part removed). As teeth 27 are enmeshed in sequence with teeth 26 as a result of the pivotal action of 18, the spur gear 25 is rotated in a counter-clockwise direction as viewed from this elevation.

In this view, ring bevel gear 17 is engageable with the pinion bevel gear 29. Teeth of ring bevel gear 17 enmesh with bevel gear teeth 30 of pinion bevel gear 29, with the resulting rotation of driveshaft 28. The upper edge of gear 29 rotating away from the viewer, the lower edge rotating toward the viewer.

The driveshaft 28 extending the length of and an adequate distance beyond the forward end of the barrel portion of the case 13 is supported therein by two sleeve bearings 31 set in openings 32 of the interior surface of the case halves 13 and 12 (part removed) when joined together.

At the extreme forward end of driveshaft 28, outside of the containment area of 13 and 12, which when joined comprise the entire case 11 (partially shown), is fitted a chuck 33, with friction grip characteristics for the purpose of holding the various adaptable screw bits for slot head screws, hex head screws, Allen head bolts and small drill bits.

FIG. 4 is a cut-away view rear end elevation with right and left halves 12 and 13 cut away at a point midway of the longitudinal axis of the gear shaft 23. Teeth 27 of gear rack 19 are shown enmeshed with 26 of spur gear 25. Gear shaft 23 with ring bevel gear 16, spur gear 25 and ring bevel gear 17 positioned thereon in sequence from left to right and secured tightly to said shaft 23 by means of set screws turned against flat areas on shaft 23 at appropriate locations. Said assembly being supported in the enclosed area of the case 11 by means of sleeve bearings 35 set in openings provided in the interior surface of halves 12 and 13. Gear rack 19 and spur gear 25 in their assembled locations obscures view of pinion bevel gear 29 located on driveshaft 28. Ring bevel gear 16 is shown held in position to enmesh with pinion gear 29 (obscured by gear 25) by .means of locking tab 34a engaged with groove 24 near end of gear shaft 23. Said position of gears results in counter-clockwise rotation of driveshaft 28 (obscured).

FIG. is a cut-away view, rear end elevation, similar 7 to FIG. 4 except that spur gear 25 and gear rack 19 are removed to show assembled location of pinion gear 29 on driveshaft 28. In this view the gear shaft 23 with center section cut-away is shifted to the left with ring bevel gear 17 held in position to enmesh with pinion bevel gear 29 by means of locking tab 34b on right side of case half 13, engaged in the groove 24 near right end of shaft 23. Said position of gears results in clockwise rotation of driveshaft 28.

In operative use, depending on the desired rotational direction of the drive shaft, for inserting or removing screws, the operator presses either protruding end of the axle shaft until it is flush with the surface of the case. He pushes down on thelocking tab 34a or 34b, each of which is a metal bar set in a narrow slot one-quarter inch below the surface of the case perpendicular to the axle shaft. The notches 35 in the lower ends of the shaft tabs will fit into the grooves 24 near the ends of the shaft and make a firm enmesh of corresponding ring gears with the pinion gear 29. For example, a clock-wise direction of drive shaft movement is desired to install a screw. By pushing the shaft on the right side of the case and securing the locking tab, then grasping the handle of the tool like a pistol and with all four fingers inserted on the finger-grip, the same is squeezed toward the handle, the gear rack enmeshing with the lower side of the center gear 25, turning it forward. The right side of the ring gear 17 will enmesh with the pinion gear. Downward turn of the ring gear at the forward perimeter result in clockwise or righthand rotation of the pinion gear and drive shaft. When the last tooth of the gear rack is reached, the power stroke is completed. By exerting pressure on the finger guard with the backsides of the fingers, the trigger is returned to the original position. Due to the angle of the teeth on the gear rack and center gear, plus a spring action in the rack, shaft will remain fixed on the return stroke, undisturbed shaft and tool bit position resulting.

The tool can be manufactured in two models with different gear ratios to result in a low speed, high torque model, and a high speed, low torque model for extreme varying needs of the tool.

While various changes may be made in the detailed construction, it is understood that such changes will 4 be within the spirit and scope of the present invention as is defined by the appended claims.

I claim:

1. In a palm power screw wrench, the combination of a hollow case, the exterior surface of which is shaped in a manner to fit the contour of the average sized human hand in a gripping position, said hollow case being com prised of a right and left hand half, said case including a central compartment for containing a mechanism to rotate a drive shaft, said mechanism including a pair of ring bevel gears on a gear shaft, a spur gear upon said gear shaft between said ring bevel gears, said ring bevel gears being spaced apart accordingly for said spur gear, a notch near each end of said gear shaft, each of said notches being engageable by a slidable locking tab carried by said case for the purpose of holding said gear shaft to either side to cause either of said ring bevel gears to engage a pinion bevel gear on said drive shaft, drive means associated with said spur gear for rotating said gear shaft to drive said drive shaft, and said drive shaft having a tool bit chuck at its opposite end.

2. The combination as set forth in claim 1 wherein a finger-grip is secured pivotally free upon a pin carried between said pistol-grip case halves, said finger-grip having an integral gear rack, said gear rack being engaged with said spur gear of said gear shaft.

3. The combination as set forth in claim 2 wherein bearings are carried in the barrel portion of said pistol grip case, said bearings supporting said drive shaft at reasonable locations near the forward and rearward ends, and said drive shaft supporting said tool bit chuck.

References Cited UNITED STATES PATENTS 2,712,765 7/1965 Knight -66 2,817,257 12/1957 Kniser 81-58 FOREIGN PATENTS 618,810 2/ 1949 Great Britain.

13,880 11/1910 Denmark.

ROBERT C. RIORDON, Primary Examiner R. V. PARKER, 111., Assistant Examiner US. Cl. X.R. 8158.1 

